(1) Technical Field
The present invention relates to field of optical and radio communications. More specifically, the present invention relates to a mechanism for generating coded optical and/or electrical frequency tones with a corresponding transceiver architecture, which may be incorporated into a multiple user code division multiple access (CDMA) communication system.
(2) Discussion
Secure optical communication systems, both fiber optic and free space, currently use several different coding and encryption schemes. One example of such a scheme is the multi-user spread spectrum code-division multiple access (CDMA) scheme. The conventional spread spectrum CDMA scheme spreads a signal over a wide and continuous frequency range according to a code. After it is received at a receiver, it is decoded using a corresponding key in order to separate a user access that user's data in the transmission.
Although the spread spectrum CDMA technique is useful for coding and encryption, it would be advantageous to provide a discrete CDMA wavelength spreading technique that uses combinations of discrete optical wavelengths produced by an optical comb generator to encode each user's data by permutation. Such a technique would provide for a greater number of user codes and a greater flexibility for dynamic code generation/alteration. Additionally, such a technique would lead to reduced signal detection complexity at the receiver (and accordingly equipment complexity) as well as increasing the received signal to noise ratio, which would thereby enhance signal quality.